Are longer sleeps (in C++) less precise than short ones

Question

I have a task to do something every \"round\" minute(at xx:xx:00) And I use something like

const int statisticsInterval=60;
    time_t t=0;
    while (1)
            


        

Answer 1

The answer is yes. It has nothing to do with C++ however. It has everything to do with the operating system.

Because of the greater focus on low power use in current portable systems, the operating systems have been getting smarter about timers.

Both Windows and Linux use timer slack in order to avoid waking up too often. This slack is automatically calculated using the timeout duration. It can be overridden in various ways if a really accurate timer is absolutely required.

What this does for the operating system is to allow it to get into really deep sleep states. If timers are going off all of the time, the CPU and RAM don't get a chance to power down. But if timers are collected together into a batch, the CPU can power up, run all of the timer operations, then power down again.

So if there are 10 programs all sleeping for 60 seconds but offset by a half-second or so, the most efficient use of the CPU is to wake up one time, run all 10 timers and then go back to sleep instead of waking up 10 times.